1. Technical Field
The present invention is related to a linear direct current motor, in particular, to a voice coil motor.
2. Description of Related Art
A voice coil motor is a type of linear direct current motor, utilizing permanent magnets and magnetic-field coils to form an actuator having the properties of direct actuation and fixed strokes. The basics of voice coil motor is simple and due to its simplicity in structures, it is particularly suited to the positioning control of short stroke and high precision. One of the common application is the use of such voice coil motor in auto-focus system of a built-in camera in mobile phones.
As the trend is to have lighter and thinner mobile phones, voice coil motors too need to of smaller sizes to be accommodated in such mobile phones. However, as the size of the voice coil motors decreases, the assembly of such motor becomes harder and poses difficulties to manual assembly.
As shown in FIGS. 1 and 2, the structure of a known voice coil motor comprises a base 1, two conductive legs 2 and a conductive spring plate 3. The conductive legs 2 are inserted into the slots 4 on the base 1 manually. However, as the components of conductive legs 2 are small in size, the assembly and manufacturing of such small components are difficult, and if the assembly tolerance becomes greater, the welding between the conductive legs 2 and external power source becomes even more difficult. In addition, since the conductive legs 2 are being welded onto the conducive spring plate 3 with a small area provided by its top surface 5, the manufacturing process is difficult and the defective rate is also high.
Therefore, it can be understood that known coil motors have their drawbacks and downsides in the structural designs to be overcome and improved.